An automatic rifle is capable of self-loading, burst fire mode, and fully automatic firing. It uses its recoil or a portion of the gas propelling a projectile to remove old spent cartridge cases, load a new cartridge and fire again. Hence, once its trigger is pulled, the automatic rifle will start burst firing, and the burst firing will not stop until the rifle runs out of bullets.
Automatic rifle manufacturers care about the optimization and quality of their automatic rifles. The dimensions of all the parts and components of conventional automatic rifles must be precisely calculated and corrected for the sake of practicability, durability, and precision. The type of bullets for use in automatic rifles depends on the model numbers of the automatic rifles. As a result, there is limited universality of parts and components between conventional automatic rifles.
Firearms in use among civilians nowadays in Europe and North America are mostly AR-15 automatic rifles, 0.22 inch caliber automatic rifles, handguns, etc. AR-15 automatic rifles use bullets which are 5.56 mm in caliber and 45 mm in length, whereas 0.22 inch caliber automatic rifles use bullets which are 0.22 inch in caliber. The great difference in applicable bullets between an AR-15 automatic rifle and a 0.22 inch caliber automatic rifle renders it impossible for an AR-15 automatic rifle and a 0.22 inch caliber automatic rifle to use the same bullet. As a result, AR-15 automatic rifles differ from 0.22 inch caliber automatic rifles in a cartridge, an action, a barrel and even a gun body. Therefore, rifle users must choose bullets in accordance with the equipment in use.
The bullets for use with AR-15 automatic rifles surpass the bullets for use with Ruger 10/22 automatic rifles in caliber, length, quantity of gunpowder contained, and firing range. Hence, AR-15 automatic rifles are suitable for use in medium- and long-distance field combats. By contrast, although the bullets for use with Ruger 10/22 automatic rifles are disadvantageously dwarfed by their counterparts in caliber, length, quantity of gunpowder contained, and firing range, the bullets for use with Ruger 10/22 automatic rifles have their advantages, namely low recoil, low noise, and low manufacturing costs. Therefore, the bullets for use with Ruger 10/22 automatic rifles are commonly used with private hunting in Europe and North America. However, according to a limit of the firearm, more than two bullets cannot be adapted in the same rifle. It is important to overcome the aforesaid drawbacks of the prior art.